The present invention relates to a sheet reversing device which turns a sheet.
Conventionally, as an example of a sheet reversing device which turns a sheet, a sheet reversing unit applied to a sheet-fed offset rotary printing press equipped with a reversing mechanism, which is capable of printing on one or both of the two surfaces of a sheet, has been proposed, as described in Japanese Patent Laid-Open No. 58-219058. Such a conventional reversing unit is interposed between first and second, adjacent printing units, and performs a selective reversing operation for a sheet to allow single-sided printing and double-sided printing on the sheet.
The conventional sheet-fed offset rotary printing press equipped with a reversing mechanism uses air blowing or suction to prevent the trailing edge of a sheet from fluttering in holding it by a reversing unit. However, this arrangement is complicated as it requires an air device formed by, for example, an air source, pipe, and nozzle for air discharge or suction. This arrangement also requires adjusting the air pressure in accordance with, for example, the material of a sheet, and therefore imposes a heavy burden on the operator. In this case, if the air pressure is not adjusted, the position at which the sheet is held by the reversing unit shifts to degrade the front and back registration accuracy, or the trailing edge of the sheet cannot be held to cause a conveyance failure. Such a problem is posed not only in the printing press but also in processing machines which process the sheet, such as a coating machine and inspection machine.